Touch panel, display device, and electronic apparatus

ABSTRACT

Disclosed herein is a touch panel including: a sensor substrate and a cover substrate stuck to each other. The sensor substrate includes a sensor electrode, and plural signal wirings electrically connected to the sensor electrode and extending along a periphery of the sensor electrode. The cover substrate includes one or plural conductive layers extending along the periphery of the sensor electrode and the plural signal wirings within an area not facing the sensor electrode and the plural signal wirings.

CROSS REFERENCE TO RELATED APPLICATIONS

The present Application is a Continuation Application of U.S.application Ser. No. 13/682,273, filed Nov. 20, 2012 and which claimspriority from Japanese Priority Application JP 2012-024896 filed in theJapan Patent Office on Feb. 8, 2012, the entire contents of which arehereby incorporated by reference in their entirety.

BACKGROUND

The present disclosure relates to a touch panel which is capable ofdetecting a position where an object such as a finger, a hand, an arm ora pen (hereinafter referred to as “a finger or the like”) touches adetection surface thereof, a display device including the touch panel,and an electronic apparatus including the display device.

Heretofore, there have been known techniques with each of whichinformation is inputted by touching a detection surface with a finger orthe like. Of these techniques, as the technique which receivesespecially attention, there is known a display device which can carryout information input similar to the case where a normal button isdepressed with the finger or the like by touching images of variouskinds of button displayed on the display with the finger or the like.The technique relating to this display device provides large merits suchas space saving and reduction of the number of parts and componentsbecause the common use of the display and the buttons is made possible.

With regard to the touch panel for detecting the contact of the fingeror the like, various types of touch panels exist. In this case, anelectrostatic capacitance type touch panel is given as the touch panelwhich generally comes into wide use in a device, such as a smartphone,requiring multi-point detection. This electrostatic capacitance typetouch panel, for example, is described in Japanese Patent Laid-Open No.2011-198207. This electrostatic capacitance type touch panel includes amatrix-like electrode pattern within a detection surface, and is adaptedto detect a change in an electrostatic capacitance in a position on adetection surface where the detection surface is touched with the fingeror the like.

SUMMARY

Now, in the electrostatic capacitance type touch panel, circuitdestruction and a malfunction due to Electro-Static Discharge (ESD)become serious problems. Normally, for the purpose of preventing the ESDfrom being generated, for example, in a liquid crystal display device,it is well known to provide a guard ring. This technique, for example,is described in Japanese Patent Laid-Open No. 2011-232641. In the touchpanel as well, similarly to the case of the liquid crystal displaydevice, it is expected that a guard ring is provided within the samelayer as that of a sensor electrode in an outer peripheral portion ofthe sensor electrode. However, there is caused a problem that when theguard ring is provided in such a position, a frame of the touch panel iswidened all the more because the guard ring is provided.

The present disclosure has been made in order to solve the problemsdescribed above, and it is therefore desirable to provide a touch panelwhich is capable of taking the measures to cope with ESD withoutwidening a frame of the touch panel, a display device including thetouch panel, and an electronic apparatus including the display device.

In order to attain the desire described above, according to anembodiment of the present disclosure, there is provided a touch panelincluding: a sensor substrate and a cover substrate stuck to each other.The sensor substrate includes a sensor electrode, and plural signalwirings electrically connected to the sensor electrode and extendingalong a periphery of the sensor electrode. The cover substrate includesone or plural conductive layers extending along the periphery of thesensor electrode and the plural signal wirings within an area not facingthe sensor electrode and the plural signal wirings.

According to another embodiment of the present disclosure, there isprovided a display device. The display device includes: an imagegenerating device configured to generate an image; a touch paneldisposed on a surface of the image generating device; and a controllerconfigured to control the image generating device and the touch panel.The touch panel includes a sensor substrate and a cover substrate stuckto each other. The sensor substrate includes a sensor electrode, andplural signal wirings electrically connected to the sensor electrode andextending along a periphery of the sensor electrode. The cover substrateincludes one or plural conductive layers extending along the peripheryof the sensor electrode and the plural signal wirings within an area notfacing the sensor electrode and the plural signal wirings.

According to still another embodiment of the present disclosure, thereis provided an electronic apparatus. The electronic apparatus includes adisplay device. The display device includes an image generating deviceconfigured to generate an image, a touch panel disposed on a surface ofthe image generating device, and a controller configured to control theimage generating device and the touch panel. The touch panel includes asensor substrate and a cover substrate stuck to each other. The sensorsubstrate includes a sensor electrode, and plural signal wiringselectrically connected to the sensor electrode and extending along aperiphery of the sensor electrode. The cover substrate includes one orplural conductive layers extending along the periphery of the sensorelectrode and the plural signal wirings within an area not facing thesensor electrode and the plural signal wirings.

In the touch panel according to the embodiment of the presentdisclosure, the display device according to another embodiment of thepresent disclosure, and the electronic apparatus according to stillanother embodiment of the present disclosure, the one or pluralconductive layers extending along the periphery of the sensor electrodeand the plural signal wirings are provided within the area not facingthe sensor electrode and the plural signal wirings. As a result, the oneor plural conductive layers function as a guard ring for the measuretaken to cope with the ESD. In addition, in the present disclosure, theone or plural conductive layers are provided on the cover substrate.Here, in the cover substrate, the periphery of the sensor electrode andthe plural signal wirings is normally an area in which a fixing layer isprovided which is used when the touch panel is stuck to a chassis or thelike. In a word, in the present disclosure, the one or plural conductivelayers functioning as the guard ring for the countermeasure taken tocope with the ESD are provided within the area in which the fixing layerdescribed above is provided. Therefore, it is unnecessary to newlyprovide a space for the guard ring for the countermeasure taken to copewith the ESD in an in-plane layout of the touch panel.

As set forth hereinabove, according to the present disclosure, in thein-plane layout of the touch panel, it is unnecessary to newly providethe space for the guard ring for the countermeasure taken to cope withthe ESD. Therefore, it is possible to take the measure to cope with theESD without widening the frame of the touch panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are respectively a cross sectional view schematicallyshowing a structure of a touch sensor and explaining the basicprinciples of an operation detection system used in a display deviceaccording to a first embodiment of the present disclosure in a state ofnon-contact, and a circuit diagram showing an equivalent circuit of thetouch sensor shown in FIG. 1A, and a peripheral circuit connected to thetouch sensor in the state of the non-contact;

FIGS. 2A and 2B are respectively waveform charts, of a detected signaland a drive signal for the touch sensor, explaining the operationprinciples of the touch detection system used in the display deviceaccording to the first embodiment of the present disclosure;

FIGS. 3A and 3B are respectively a cross sectional view schematicallyshowing the structure of the touch sensor and explaining the basicprinciples of the operation of the touch detection system used in thedisplay device according to the first embodiment of the presentdisclosure in a state of finger contact, and the peripheral circuitconnected to the touch sensor in the state of the finger contact;

FIG. 4 is a cross sectional view showing a cross-sectional structure ofthe display device according to the first embodiment of the presentdisclosure;

FIG. 5 is a cross sectional view showing a cross-sectional structure ofa touch panel shown in FIG. 4;

FIG. 6 is a top plan view showing a layout of an electrode pattern ofthe touch panel shown in FIG. 5;

FIG. 7 is a cross sectional view showing a cross-sectional view of aFlexible Printed Circuits (FPC) shown in FIG. 6;

FIG. 8 is a top plan view showing an electrode pattern of the touchpanel shown in FIG. 5, and a layout of conductive layers on a coversubstrate side;

FIG. 9 is a top plan view showing an electrode pattern of the touchpanel shown in FIG. 5, and a layout of a fixing layer on the coversubstrate side;

FIG. 10 is a cross sectional view explaining a method of manufacturingthe display device of the first embodiment including the touch panelshown in FIG. 5;

FIG. 11 is a top plan view showing an electrode pattern of the touchpanel, and a layout of the conductive layers on the cover substrate sideaccording to a first modified change of the first embodiment of thepresent disclosure;

FIG. 12 is a cross sectional view showing a cross-sectional structure ofthe touch panel, shown in FIG. 4, according to a second modified changeof the first embodiment of the present disclosure; and

FIG. 13 is a perspective view showing a construction of an electronicapparatus according to an example of application to which the displaydevice according to the first embodiment of the present disclosure isapplied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present disclosure will be described in detailhereinafter with reference to the accompanying drawings. It is notedthat the description will be given below in accordance with thefollowing order.

1. Basic Principles of Touch Detection System

2. First Embodiment (Display Device)

3. Modified Changes

4. Second Embodiment (Touch Panel)

5. Third Embodiment (Electronic Apparatus)

6. Example of Application

1. Basic Principles of Touch Detection System

Firstly, a description will be given with respect to the basicprinciples of a touch detection system used in a display deviceaccording to a first embodiment of the present disclosure. This touchdetection system is embodied in the form of an electrostatic capacitancetype touch sensor. FIG. 1A is a cross sectional view schematicallyshowing a structure of the touch sensor described above in a state ofnon-contact. Also, FIG. 1B is a circuit diagram showing an equivalentcircuit of the touch sensor shown in FIG. 1A, and a peripheral circuitwhich is connected to the touch sensor. The touch sensor includes adielectric 101, and a pair of electrodes 102 and 103 which are disposedso as to hold the dielectric 101 between them, and so as to face eachother. The dielectric 101, and the pair of electrodes 102 and 103 areexpressed in the form of a capacitative element 104 in the equivalentcircuit as shown in FIG. 1B.

One terminal, that is, the electrode 102 of the capacitative element 104is connected to an alternate-current signal source 105. The otherterminal, that is, the electrode 103 of the capacitative element 104 isconnected to a voltage detecting circuit 106, and is further connectedto a reference electric potential line 108 through a resistor 107. Thealternate-current signal source 105 outputs an alternate-currentrectangular wave signal Sg having a predetermined frequency (forexample, in the range of about several kHz to about more than ten kHz).The voltage detecting circuit 106 detects a crest value of a signalinputted thereto, and determines whether or not a finger of a usertouches the touch sensor in accordance with the detected voltage. Thereference electric potential line 108, for example, is electricallyconnected to a member (for example, a grounding layer of a printedcircuit or a conductive chassis) which gives an electric potentialbecoming a reference for a circuit operation in a device to which thetouch sensor is mounted. Thus, while the reference electric potentialline 108 is electrically connected to the member concerned, thereference electric potential line 108 has the same electric potential(reference electric potential) as that of the member concerned. Thereference electric potential, for example, is the grounding electricpotential.

In the touch sensor, when the alternate-current rectangular wave signalSg (refer to FIG. 2B) is applied from the alternate-current signalsource 105 to the electrode 102, an output waveform (of a detectedsignal Vdet) as shown in FIG. 2A appears in the electrode 103.

In a state in which an object of the finger or the like does not touchthe touch sensor (refer to FIG. 1A), as shown in FIG. 1B, a current I0corresponding to a capacitative value of the capacitative element 104 iscaused to flow through the capacitative element 104 along withcharge/discharge to/from the capacitative element 104. A waveform of anelectric potential on the electrode 103 side of the capacitative element104, for example, becomes like a waveform V0 shown in FIG. 2A which isin turn detected by the voltage detecting circuit 106.

On the other hand, in a state in which the object of the finger or thelike contacts the touch sensor (refer to FIG. 3A), as shown in FIG. 3B,a capacitative element 109 formed by the object of the finger or thelike is added in series with the capacitative element 104. In thisstate, currents I1 and I2 are caused to flow through the capacitativeelements 104 and 109 along with the charge/discharge to/from thecapacitative elements 104 and 109, respectively. At this time, thewaveform of the electric potential in the electrode 103, for example,becomes like a waveform V1 shown in FIG. 2A which is in turn detected bythe voltage detecting circuit 106. The electric potential in theelectrode 103 becomes a divided electric potential which is determineddepending on values of the currents I1 and I2 which are caused to flowthrough the capacitative elements 104 and 109, respectively. For thisreason, the waveform V1 has a smaller value than that of the waveform V0in the non-contact state. After that, the voltage detecting circuit 106compares the detected voltage and a predetermined threshold voltage Vthwith each other. When it proves from the comparison result that thedetected voltage is equal to or smaller than the predetermined thresholdvoltage Vth, the state is determined to be the non-contact state. On theother hand, when it proves from the comparison result that the detectedvoltage is larger than the predetermined threshold voltage Vth, thestate is determined to be the contact state. The touch detection iscarried out in such a manner. It is noted that in a display device of afirst embodiment which will be described below, a detection systemdifferent from that described above may also be used.

2. First Embodiment (Display Device)

Structure

FIG. 4 shows a cross-sectional structure of a display device 1 accordingto a first embodiment of the present disclosure. The display device 1 ofthe first embodiment is a display device with a touch sensor, andincludes an image generating device 10, an electrostatic capacitancetype touch panel 20, and a controller 30. The touch panel 20 is formedseparately from the image generating device 10, and is disposed on asurface of the image generating device 10. The controller 30 controlsboth of the image generating device 10 and the touch panel 20.Specifically, the controller 30 drives the image generating device 10based on a video signal inputted from the outside. Also, the controller30 drives the touch panel 20 and outputs a signal corresponding to adetected signal from the touch panel 20 to the output.

Image Generating Device 10

The image generating device 10 generates an image in accordance with asignal inputted thereto from the controller 30. The image generatingdevice 10 is composed of a liquid crystal display panel and a lightsource. In this case, the liquid crystal display panel transmits andmodulates an incident light by changing an alignment of liquid crystalmolecules, thereby generating an image. Also, the light sourceilluminates the liquid crystal display panel from a back side. It isnoted that the image generating device 10 may adopt a structuredifferent from that described the above and, for example, may becomposed of an organic EL display panel for causing an organic ELelement to emit a light, thereby generating an image.

Touch Panel 20

FIG. 5 shows a cross-sectional structure of the touch panel 20. FIG. 6shows a layout of an electrode pattern of the touch panel 20. It isnoted that FIG. 5 shows the cross-sectional structure of a portion,corresponding to line A-A of FIG. 6, of the touch panel 20.

The touch panel 20 is such that an image display surface (a detectionsurface of the touch panel 20) of the display device 1 is touched by thefinger or the like, thereby inputting information. The touch panel 20,for example, corresponds to a concrete example of the electrostaticcapacitance type touch sensor described above, and detects whether ornot the finger or the like touches the detection surface with anXY-matrix. The touch panel 20, for example, is stuck to a surface ofeither a chassis (not shown) or the image generating device 10 of thedisplay device 1 through either an adhesive bonding layer or apressure-sensitive adhesive layer. Also, the touch panel 20, forexample, as shown in FIG. 5, is stuck to the surface of either thechassis (not shown) or the image generating device 10 of the displaydevice 1 through a fixing layer 40 provided in an outer edge of thetouch panel 20. Here, the fixing layer 40 is used when the touch panel20 is stuck to either the chassis (not shown) or the image generatingdevice 10 of the display device 1. The fixing layer 40 is made of amaterial having both of elasticity and viscosity and, for example, iscomposed of a pressure-sensitive adhesive tape. In addition thereto, thefixing layer 40 may be made of a material having a conductive propertyand, for example, is composed of a conductive pressure-sensitiveadhesive tape. It is noted that the fixing layer 40 may have aninsulating property.

The touch panel 20 is formed in such a way that the sensor substrate 21and the cover substrate 22 are stuck to each other through the fixinglayer 23. The fixing layer 23, for example, is formed by curing a UVcurable resin. The sensor substrate 21 and the cover substrate 22 aredisposed so as to face each other through the fixing layer (adhesivelayer) 23. The sensor substrate 21, for example, is formed in such a waythat a conductive layer 25, an insulating layer 26, and a conductivelayer 27 are laminated on an upper surface of a substrate 24 (a surfaceon the cover substrate 22 side) in this order. The cover substrate 22,for example, is formed in such a way that a light blocking layer 29, andone or plural conductive layers 31 are provided on a lower surface of asubstrate 28 (a surface on the sensor substrate 21 side). The substrate28 is larger in size than the substrate 24 and, for example, is slightlylarger in size than the substrate 24. In a word, the substrate 28 has acircular area which does not face the substrate 24.

The substrate 24 is a substrate on which the conductive layer 25, theinsulating layer 26, and the conductive layer 27 are formed in thisorder, and thus holds the conductive layer 25, the insulating layer 26,and the conductive layer 27. The substrate 24 is composed of aninsulating and light transmissive member and, for example, is composedof a glass substrate, or an insulating and light transmissive resinfilm. The substrate 28 is a substrate which composes the detectionsurface and covers the conductive layer 25 and the like. The substrate28 also holds the light blocking layer 29 and the one or pluralconductive layers 31. The substrate 28 is composed of an insulating andlight transmissive member and, for example, is composed of a glasssubstrate, or an insulating and light transmissive resin film.

The conductive layers 25 and 27 serve to detect contact/non-contact ofthe finger or the like to the detection surface. Each of the conductivelayers 25 and 27, for example, is made of a light transmissiveconductive material such as an Indium Tin Oxide (ITO). The insulatinglayer 26 is disposed between the conductive layer 25 and the conductivelayer 27. The insulating layer 26 serves to isolate a first electrode E1and a second electrode E2 which will be described later from each otherand, for example, is made of a light transmissive insulating material.The insulating layer 26 has contact holes 26A in positions correspondingto both end portions of an island-like electrode E3 which will bedescribed later, respectively. A light transmissive insulating materialused for the insulating layer 26, for example, includes an acrylic resinor an inorganic material containing therein SiO₂ and the like as aprincipal component. The light blocking layer 29 serves to preventsilhouettes of the one or plural conductive layers 31 and signal wirings21B which will be described later from being visually recognized on theimage display surface. Thus, the light blocking layer 29 is made of alight blocking material. Although a color of the light blocking materialis typically black, any other suitable color (for example, white) otherthan black may also be adopted as the color of the light blockingmaterial.

The conductive layer 25 and the conductive layer 27 are composed ofsensor electrodes 21A, and plural signal wirings 21B. In this case, thecontact/non-contact of the finger or the like to the detection surfaceis detected through the sensor electrodes 21A. Also, the sensorelectrodes 21A and the controller 30 are connected to each other throughthe plural signal wirings 21B. The sensor electrodes 21A are disposed ina position corresponding to a portion, except for the outer edge, of theupper surface of the substrate 24. The plural signal wirings 21B aredisposed in a position, corresponding to the outer edge, of the uppersurface of the substrate 24, and extend along a periphery of the sensorelectrodes 21A.

The sensor electrodes 21A are composed of plural first electrodes E1 andplural second electrodes E2. In this case, the plural first electrodesE1 extend in a predetermined direction. Also, the plural secondelectrodes E2 extend in a direction intersecting with (for example,perpendicular to) the plural first electrodes E1. Each of the pluralfirst electrodes E1 is composed of a part of the conductive layer 25. Ina word, the conductive layer 25 includes the plural first electrodes E1.The plural first electrodes E1 are formed so as to contact an uppersurface of the substrate 24 (a surface on the cover substrate 22 side).Also, plural first electrodes E1 are strip-like electrodes composed ofplural island-like electrodes and coupling electrodes through each ofwhich each adjacent two island-like electrodes are coupled to eachother. Here, a width of each of the coupling electrodes is narrower thanthat of each of the island-like electrodes.

Each of the second electrodes E2 is composed of a part of the conductivelayer 25, and all of or a part of the conductive layer 27. In a word,the conductive layer 25 is composed of all of the first electrodes E1,and a part of the second electrodes E2. Also, the conductive layer 27 iscomposed of a part of the second electrodes E2. The second electrodes E2are strip-like electrodes composed of plural island-like electrodes E3disposed in the same layer as that of the first electrodes E1, and relayelectrodes E4. In this case, each adjacent two island-like electrodes E3are electrically connected to each other through the corresponding oneof the relay electrodes E4. Also, the relay electrode E4 straddles eachadjacent two first electrodes E1 (specifically, each adjacent twocoupling electrodes). In a word, the conductive layer 25 is composed ofall of the first electrodes E1 and the island-like electrodes E3. Also,the conductive layer 27 is composed of the relay electrodes E4. Here, awidth of each of the relay electrodes E4 is narrower than that of eachof the island-like electrodes E3. In addition, the island-likeelectrodes E3, and the island-like electrodes of the first electrodes E1are disposed in a delta pattern.

Each of the relay electrodes E4 has a strip-like shape extending in anextension direction of each of the second electrodes E2. In each of therelay electrodes E4, one end thereof is connected to one island-likeelectrode E3, and the other end thereof is connected to anotherisland-like electrode E3. Also, a portion thereof straddling eachadjacent two first electrodes E1 is disposed in a layer above each ofthe first electrodes E1. “The layer above each of the first electrodesE1” means the layer contacting an upper surface of the insulating layer26, and specifically means the conductive layer 27. Therefore, each ofthe relay electrodes E4 is disposed closer to the substrate 28 than eachof the island-like electrodes E3. The relay electrodes E4 arecollectively formed in a manufacturing process and thus are composed ofa single layer. On the other hand, the island-like electrodes E3 and thefirst electrodes E1 are together formed in a common manufacturingprocess, and thus the island-like electrodes E3 and the first electrodesE1 are made of the same material.

A part of both end portions, in a longitudinal direction, of each of therelay electrodes E4 is disposed within the contact hole 26A in theinsulating layer 26. In a word, the insulating layer 26 has the contactholes 26A in the positions corresponding to the both end portions, inthe longitudinal direction, of each of the relay electrodes E4,respectively. Each of the contact holes 26A, for example, is disposed ina position where an upper surface of each of the island-like electrodesE3 is exposed within a bottom surface of the contact hole 26A.Therefore, each of the relay electrodes E4 contacts a portion, exposedwithin the control hole 26A, of each of the island-like electrodes E3and is isolated from each of the first electrodes E1 through theinsulating layer 26.

The signal wirings 21B are electrically connected to the sensorelectrodes 21A and extend along the periphery of the sensor electrodes21A. A part of the plural signal wirings 21B is electrically connectedto the first electrodes E1, and the signal wirings 21B, which areun-connected to the first electrodes E1, of the plural signal wirings21B are electrically connected to the second electrodes E2.

Next, the conductive layer 31 will be described. The conductive layer 31is provided so as to contact the surface of the light blocking layer 29.The conductive layer 31 has a width thicker than that of each of thesignal wirings 21B. The conductive layer 31 is preferably sufficientlythinner than the fixing layer 40. The conductive layer 31 is made of ametallic material and, for example, is made of a low-resistance materialsuch as a conductive paste or a silver paste. The conductive layer 31 isprovided within an area which does not face each of the sensorelectrodes 21A and the signal wirings 21B, and extends along theperiphery of the sensor electrodes 21A and the signal wirings 21B.Therefore, the conductive layer 31 functions as a guard ring for thecountermeasure taken to cope with the ESD. Here, in the cover substrate22, the periphery of the sensor electrode 21A and the signal wirings 21Bis normally an area in which the fixing layer 40 used when the touchpanel 20 is stuck to the chassis or the like is provided. In a word, oneor plural conductive layers 31 functioning as the guard ring for thecountermeasure taken to cope with the ESD are provided within the areain which the fixing layer 40 is provided. Therefore, in the in-planelayout of the touch panel 20, a space of the one or plural conductivelayers 31 is not provided so as to be dedicated to the one or pluralconductive layers 31.

The touch panel 20, as shown in FIGS. 6 and 7, further includes aFlexible Printed Circuit (FPC) connected to the sensor substrate 21, andan IC 33 disposed on the FPC 32. The FPC 32 includes a wiring layer 32Aand a fixing electric potential layer 32B. The wiring layer 32A iscomposed of plural signal wirings which, for example, are in turnelectrically connected to the signal wirings 21B on one-by-one basisthrough an Anisotropic Conductive Film (ACF), respectively. The fixingelectric potential layer 32B is formed in a large area within the FPC 32and, for example, is a layer which, for example, is set to the groundingelectric potential as a reference electric potential. The fixingelectric potential layer 32B, for example, is electrically connected tothe one or plural conductive layers 31 through a conductive paste, asilver paste or the like. In a word, the one or plural conductive layers31 have the same electric potential as that of the fixing electricpotential layer 32B.

Here, the fixing electric potential layer 32B, and the one or pluralconductive layers 31, for example, are electrically connected to eachother through a low-resistance material such as a conductive paste or asilver paste. A resistance value of the low-resistance material such asa conductive paste or a silver paste is equal to that of each of thefixing electric potential layer 32B, and the one or plural conductivelayers 31. For this reason, when a current due to the ESD is caused toflow from the one or plural conductive layers 31 to the fixing electricpotential layer 32B through the low-resistance material such as aconductive paste or a silver paste, the low-resistance material such asa conductive paste or a silver paste is prevented from becoming aresistor to be heated. It is noted that although the ACF is also alow-resistance material, a resistance value of the ACF is slightlylarger than that of the low-resistance material such as a conductivepaste or a silver paste. Therefore, it is not preferable so much thatthe ACF is used in a portion through which the current due to the ESD iscaused to flow.

FIG. 8 is a top plan view showing the electrode pattern of the touchpanel 20, and a layout of the one or plural conductive layers 31. FIG. 9is a top plan view showing the electrode pattern of the touch panel 20,and a layout of the fixing layer 40. The one or plural conductive layers31 and the fixing layer 40 extend along the periphery of the sensorelectrodes 21A and the signal wirings 21B. The one or plural conductivelayers 31 and the fixing layer 40, for example, are cut out in thevicinity of the FPC 32 in order to avoid the interference with the IC33.

Manufacturing Method

Next, a description will now be given with respect to a method ofmanufacturing the display device 1 according to the first embodiment ofthe present disclosure. Firstly, the sensor substrate 21 including thesensor electrodes 21A and the plural signal wirings 21B is prepared aswell as the cover substrate 22 including the one or plural conductivelayers 31 and the light blocking layer 29 is prepared (refer to FIG.10). At this time, as shown in FIG. 10, an ultraviolet curable resin 23Dis applied onto the cover substrate 22. In addition, the fixing layer 40is previously stuck to the one or plural conductive layers 31. Next, asshown in FIG. 10, the sensor substrate 21 and the cover substrate 22 arestuck to each other through the ultraviolet curable resin 23D.

Next, for example, an ultraviolet light is radiated from the coversubstrate 22 side, thereby curing the ultraviolet curable resin 23D. Asa result, the sensor substrate 21 and the cover substrate 22 are fixedto each other by the fixing layer 23. The touch panel 20 is completed insuch a manner. Next, for example, the touch panel 20, and the chassis orthe image generating device 10 are stuck to each other through thefixing layer 40 provided in the outer edge of the touch panel 20. Afterthat, although not illustrated, the controller 30 is connected to bothof the touch panel 20 and the image generating device 10. The displaydevice 1 is completed in such a manner.

It is noted that with regard to the fixing layer 40, after the sensorsubstrate 21 and the cover substrate 22 may be stuck to each otherthrough the ultraviolet curable resin 23D, the sensor substrate 21 andthe cover substrate 22 thus stuck to each other may be stuck to theconductive layer 31.

Operation

Next, a description will now be given with respect to an operation ofthe display device 1 according to the first embodiment of the presentdisclosure. Firstly, for example, the controller 30 starts an operationof the touch panel 20 by activating a power source of the display device1. Firstly, the controller 30 selects corresponding one(s) from the oneor plural electrodes (the first electrodes E1 and the second electrodesE2) included in the sensor electrodes 21A and applies analternate-current signal to the electrode(s) thus selected. At thistime, if the finger or the like contacts the detection surface, thecontroller 30 detects a change in the electrostatic capacitancegenerated in the sensor electrodes 21A by the contact of the finger orthe like to the detection surface in the form of a change in an outputvoltage. The controller 30 derives the coordinates of the position wherethe finger or the like contacts the detection surface based on theinformation on the output voltage thus detected (or the change in theoutput voltage). Thus, the controller 30 outputs information on thederived coordinates of the position where the finger or the likecontacts the detection surface to the outside.

Effects

Next, a description will now be given with respect to the effects of thedisplay device 1 according to the first embodiment of the presentdisclosure. In the first embodiment of the present disclosure, the oneor plural conductive layers 31 extending along the periphery of thesensor electrodes 21A and the signal wirings 21B are provided within thearea which does not face the sensor electrodes 21A and the signalwirings 21B. As a result, the one or plural conductive layers 31function as the guard ring for the countermeasure taken to cope with theESD. In addition, in the first embodiment of the present disclosure, theone or plural conductive layers 31 are provided on the cover substrate22. Here, in the cover substrate 22, the periphery of the sensorelectrode 21A and the signal wirings 21B is normally the area in whichthe fixing layer 40 used when the touch panel 20 is stuck to the chassisor the like is provided. In a word, in the first embodiment of thepresent disclosure, the one or plural conductive layers 31 functioningas the guard ring for the countermeasure taken to cope with the ESD areprovided within the area in which the fixing layer 40 is provided. Forthis reason, in the in-plane layout of the touch panel 20, the space ofthe one or plural conductive layers 31 needs not be newly provided. As aresult, it is possible to take the measures to cope with the ESD withoutwidening the frame of the touch panel 20.

3. Modified Changes

Although the present disclosure has been described so far by giving thefirst embodiment, the present disclosure is by no means limited to thefirst embodiment and thus various kinds of modified changes thereof canbe made.

First Modified Change

For example, in the first embodiment described above, the case where oneconductive layer 31 extends along the periphery of the sensor electrodes21A and the signal wirings 21B is exemplified. For example, however, asshown in FIG. 11, plural conductive layers 31 may extend along theperiphery of the sensor electrodes 21A and the signal wirings 21B. Inthis case, however, each of the plural conductive layers 31 ispreferably electrically connected to the fixing electric potential layer32B of the FPC 32.

Second Modified Change

In each of the first embodiment and the first modified change thereofdescribed above, the one or plural conductive layers 31 are provided onthe cover substrate 22. For example, however, as shown in FIG. 12, theone or plural conductive layers 31 may be removed away. In this case,however, the fixing layer 40 needs to have the conductive property.Here, the fixing layer 40 is preferably electrically connected to theportion having either the reference electric potential or the fixedelectric potential and, for example, preferably contacts the chassishaving the grounding electric potential.

4. Second Embodiment (Touch Panel)

The touch panel 20 according to a second embodiment of the presentdisclosure, as described above, includes the sensor substrate 21 and thecover substrate 22 stuck to each other. In this case, the sensorsubstrate 21 includes the sensor electrode 21A, and the plural signalwirings 21B electrically connected to the sensor electrode 21A andextending along the periphery of the sensor electrode 21A. Also, thecover substrate 22 includes the one or plural conductive layers 31extending along the periphery of the sensor electrode 21 and the pluralsignal wirings 21B within the area which does not face the sensorelectrode 21 and the plural signal wirings 21B.

5. Third Embodiment (Electronic Apparatus)

An electronic apparatus according to a third embodiment of the presentdisclosure includes the display device 1 of the first embodiment. Inthis case, the display device 1, as described above, includes the imagegenerating device 10 for generating an image, the touch panel 20disposed on the surface of the image generating device 10, and thecontroller 30 for controlling the image generating device 10 and thetouch panel 20. Also, the touch panel 20 includes the sensor substrate21 and the cover substrate 22 stuck to each other. In this case, thesensor substrate 21 includes the sensor electrode 21A, and the pluralsignal wirings 21B electrically connected to the sensor electrode 21Aand extending along the periphery of the sensor electrode 21A. Also, thecover substrate 22 includes the one or plural conductive layers 31extending along the periphery of the sensor electrode 21 and the pluralsignal wirings 21B within the area which does not face the sensorelectrode 21 and the plural signal wirings 21B.

It is noted that the electronic apparatus of the third embodimentincluding the display device 1 of the first embodiment, for example,includes a mobile phone, a personal computer, a liquid crystaltelevision set, a view finder type or monitor direct-view-type videotape recorder, a car navigation device, a pager, an electronic databook,a calculator, a word processor, a work station, a TV telephone set, aPOS terminal device, and the like.

It is noted that although the electronic apparatus of the thirdembodiment includes the display device 1 of the first embodiment,alternatively, the electronic apparatus of the third embodiment can alsoinclude any of the display devices according to the first and secondmodified examples of the first embodiment.

6. Example of Application

Next, a description will be given below with respect to an example ofapplication in which the display device 1 of the first embodiment isapplied to the electronic apparatus of the third embodiment. FIG. 13 isa perspective view showing a schematic construction of an electronicapparatus 100 according to the example of application. The electronicapparatus 100 is a mobile phone. For example, as shown in FIG. 13, theelectronic apparatus 100 includes a main body portion 111 and a displayportion 112 which is provided so as to be openable and closable for themain body portion 111. The main body portion 111 includes a manipulationbutton 115 and a transmitter portion 116. The display portion 112includes a display device 113 and a receiver portion 117. The displaydevice 113 is adapted to display various kinds of displays abouttelephone communications on a display screen 114 of the display device113. The electronic apparatus 100 includes a control portion (not shown)for controlling an operation of the display device 113. The controlportion is provided either as a part of a control section for takingcharge of control for the entire electronic apparatus 110 or separatelyfrom the control section inside either the main body portion 111 or thedisplay portion 112.

The display device 113 has the same structure and configuration as thoseof the display device 1 according to the first embodiment of the presentdisclosure. As a result, since it is possible to narrow the frame of thedisplay device 1, it is possible to widen the image display surface orit is possible to miniaturize the electronic apparatus 100 all the morebecause the frame of the display device 1 is narrowed.

Although the display device 1 of the first embodiment is applied as theexample of application to the electronic apparatus, alternatively, thedisplay device according to any of the first and second modifiedexamples of the first embodiment can also be applied as another exampleof application to the electronic apparatus.

In addition, for example, the present disclosure can also adopt thefollowing constitutions.

(1) A touch panel including: a sensor substrate and a cover substratestuck to each other, in which the sensor substrate includes a sensorelectrode, and plural signal wirings electrically connected to thesensor electrode and extending along a periphery of the sensorelectrode; and the cover substrate includes one or plural conductivelayers extending along the periphery of the sensor electrode and theplural signal wirings within an area not facing the sensor electrode andthe plural signal wirings.

(2) The touch panel described in the paragraph (1), in which each of theone or plural conductive layers has a thicker width than that of each ofthe plural signal wirings.

(3) The touch panel described in the paragraph (1) or (2), in which eachof the one or plural conductive layers is made of a metallic material.

(4) The touch panel described in any one of the paragraphs (1) to (3),further including a flexible printed wiring board connected to thesensor substrate, and having a wiring layer electrically connected tothe plural signal wirings, and a fixed electric potential layerelectrically connected to the one or plural conductive layers.

(5) The touch panel described in the paragraph (1) or (2), in which eachof the one or plural conductive layers is made of a material having aconductive property, elasticity, and viscosity.

(6) A display device, including: an image generating device configuredto generate an image; a touch panel disposed on a surface of the imagegenerating device; and a controller configured to control the imagegenerating device and the touch panel, wherein the touch panel includesa sensor substrate and a cover substrate stuck to each other, the sensorsubstrate including a sensor electrode, and plural signal wiringselectrically connected to the sensor electrode and extending along aperiphery of the sensor electrode, the cover substrate including one orplural conductive layers extending along the periphery of the sensorelectrode and the plural signal wirings within an area not facing thesensor electrode and the plural signal wirings.

(7) An electronic apparatus, including: a display device including animage generating device configured to generate an image, a touch paneldisposed on a surface of the image generating device, and a controllerconfigured to control the image generating device and the touch panel,wherein the touch panel includes a sensor substrate and a coversubstrate stuck to each other, the sensor substrate including a sensorelectrode, and plural signal wirings electrically connected to thesensor electrode and extending along a periphery of the sensorelectrode, the cover substrate including one or plural conductive layersextending along the periphery of the sensor electrode and the pluralsignal wirings within an area not facing the sensor electrode and theplural signal wirings.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A touch panel, comprising: a sensor substratehaving a first substrate including an insulating and light transmissivemember having a first lower side and a first upper side opposite to thefirst lower side, a sensor electrode disposed on the first upper side ina sensor area, and a plurality of signal wires disposed on the firstupper side and electrically connected to the sensor electrode andextending along a periphery of the sensor electrode on the firstsubstrate; and a cover substrate having a second substrate that isopposed to the first substrate and that has a second lower side and asecond upper side opposite to the second lower side, the second lowerside of the second substrate facing the first upper side of the firstsubstrate, one or more conductive layers disposed in a peripheral areathat is outside the sensor area, on the second lower side without directcontact with the second substrate, and a light blocking layer disposedbetween the one or more conductive layers and the second substrate,wherein, in a plan view, the second substrate overlaps the firstsubstrate in an overlapping area including the sensor area and a part ofthe peripheral area, wherein, the signal wires are disposed in theoverlapping area in the peripheral area of the first substrate, and theone or more conductive layers are disposed outside the signal wires in aplan view in the peripheral area of the second substrate, and whereinthe one or more conductive layers are applied with a reference voltagesupplied directly from outside of the touch panel.
 2. The touch panelaccording to claim 1, wherein each of the one or more conductive layershas a thicker width than that of each of the signal wires.
 3. The touchpanel according to claim 1, wherein each of the one or more conductivelayers is made of a metallic material.
 4. The touch panel according toclaim 3, further comprising: a flexible printed wiring board connectedto the sensor substrate, and having a wiring layer electricallyconnected to the signal wires, and a fixed electric potential layer thatis supplied with the reference voltage and electrically connected to theone or more conductive layers.
 5. The touch panel according to claim 1,wherein each of the one or more conductive layers is made of a materialhaving a conductive property, elasticity, and viscosity.
 6. A displaydevice, comprising: an image generating device configured to generate animage; a touch panel disposed on a surface of the image generatingdevice; and a controller configured to control the image generatingdevice and the touch panel, the touch panel including: a sensorsubstrate having a first substrate including an insulating and lighttransmissive member having a first lower side and a first upper sideopposite to the first lower side, a sensor electrode disposed on thefirst upper side in a sensor area, and a plurality of signal wiresdisposed on the first upper side and electrically connected to thesensor electrode and extending along a periphery of the sensor electrodeon the first substrate; and a cover substrate having a second substratethat is opposed to the first substrate and that has a second lower sideand a second upper side opposite to the second lower side, the secondlower side of the second substrate facing the first upper side of thefirst substrate, one or more conductive layers disposed in a peripheralarea that is outside the sensor area, on the second lower side withoutdirect contact with the second substrate, and a light blocking layerdisposed between the one or more conductive layers and the secondsubstrate, wherein, in a plan view, the second substrate overlaps thefirst substrate in an overlapping area including the sensor area and apart of the peripheral area, wherein, the signal wires are disposed inthe overlapping area in the peripheral area of the first substrate, andthe one or more conductive layers are disposed outside the signal wiresin a plan view in the peripheral area of the second substrate, andwherein the one or more conductive layers are applied with a referencevoltage supplied directly from outside of the touch panel.
 7. Anelectronic apparatus, comprising: a display device, including an imagegenerating device configured to generate an image, a touch paneldisposed on a surface of the image generating device, and a controllerconfigured to control the image generating device and the touch panel,the touch panel including: a sensor substrate having a first substrateincluding an insulating and light transmissive member having a firstlower side and a first upper side opposite to the first lower side, asensor electrode disposed on the first upper side in a sensor area, anda plurality of signal wires disposed on the first upper side andelectrically connected to the sensor electrode and extending along aperiphery of the sensor electrode on the first substrate; and a coversubstrate having a second substrate that is opposed to the firstsubstrate and that has a second lower side and a second upper sideopposite to the second lower side, the second lower side of the secondsubstrate facing the first upper side of the first substrate, one ormore conductive layers disposed in a peripheral area that is outside thesensor area, on the second lower side without direct contact with thesecond substrate, and a light blocking layer disposed between the one ormore conductive layers and the second substrate wherein, in a plan view,the second substrate overlaps the first substrate in an overlapping areaincluding the sensor area and a part of the peripheral area, wherein, the signal wires are disposed in the overlapping area in the peripheralarea of the first substrate, and  the one or more conductive layers aredisposed outside the signal wires in a plan view in the peripheral areaof the second substrate, and  wherein the one or more conductive layersare applied with a reference voltage supplied directly from outside ofthe touch panel.
 8. The touch panel according to claim 1, wherein asecond fixing layer is used when the touch panel is connected to eithera chassis or an image generating device of a display device, and thesecond fixing layer is disposed along the periphery of the sensorelectrode and the signal wires.
 9. The touch panel according to claim 1,further comprising: a flexible printed wiring board connected to thesensor substrate; and an integrated circuit disposed on the flexibleprinted wiring board, wherein a surface area of the cover substrate islarger than that of the sensor substrate, a second fixing layer is usedwhen the touch panel is connected to either a chassis or an imagegenerating device of a display device, the second fixing layer isdisposed along the periphery of the sensor electrode and the signalwires the one or more conductive layers are disposed in a region inwhich the second fixing layer is disposed, the one or more conductivelayers and the second fixing layer are cut out in a vicinity of theintegrated circuit, and the integrated circuit is disposed between theone or more conductive layers that are cut out and between the secondfixing layer that is cut out.
 10. The touch panel according to claim 1,wherein the light blocking layer faces the signal wires, the one or moreconductive layers and a second fixing layer, and the second substrate,the light blocking layer, the one or more conductive layers and thesecond fixing layer are arranged in this order.
 11. The electronicapparatus according to claim 7, wherein the light blocking layer facesthe signal wires, the one or more conductive layers and a second fixinglayer, and the second substrate, the light blocking layer, the one ormore conductive layers and the second fixing layer are arranged in thisorder.
 12. The display device according to claim 6, wherein each of theone or more conductive layers has a thicker width than that of each ofthe signal wires.
 13. The display device according to claim 6, whereineach of the one or more conductive layers is made of a metallicmaterial.
 14. The display device according to claim 14, wherein thetouch panel further includes a flexible printed wiring board connectedto the sensor substrate and having a wiring layer electrically connectedto the signal wires, and a fixed electric potential layer that issupplied with the reference voltage and electrically connected to theone or more conductive layers.
 15. The display device according to claim6, wherein each of the one or more conductive layers is made of amaterial having a conductive property, elasticity, and viscosity. 16.The display device according to claim 6, wherein a second fixing layeris used when the touch panel is connected to either a chassis or theimage generating device of the display device, and the second fixinglayer is disposed along the periphery of the sensor electrode and thesignal wires.
 17. The display device according to claim 6, furthercomprising: a flexible printed wiring board connected to the sensorsubstrate; and an integrated circuit disposed on the flexible printedwiring board, wherein a surface area of the cover substrate is largerthan that of the sensor substrate, a second fixing layer is used whenthe touch panel is connected to either a chassis or the image generatingdevice of the display device, the second fixing layer is disposed alongthe periphery of the sensor electrode and the signal wires the one ormore conductive layers are disposed in a region in which the secondfixing layer is disposed, the one or more conductive layers and thesecond fixing layer are cut out in a vicinity of the integrated circuit,and the integrated circuit is disposed between the one or moreconductive layers that are cut out and between the second fixing layerthat is cut out.
 18. The touch panel according to claim 1, furthercomprising: a flexible printed wiring board connected to the sensorsubstrate; and an integrated circuit disposed on the flexible printedwiring board, wherein the one or more conductive layers are cut out in afirst cutout area that is in a vicinity of the integrated circuit and ina second cutout area that is at an opposite end of the touch panel tothe first cutout area.
 19. The touch panel according to claim 1, furthercomprising a second fixing layer that encapsulates the one or moreconductive layers with the light blocking layer.
 20. The display deviceaccording to claim 6, wherein the touch panel further includes a secondfixing layer that encapsulates the one or more conductive layers withlight blocking layer.